In recent years, a technique referred to as OpenFlow has been proposed (see Patent Literature 1 and Non Patent Literatures 1 and 2). OpenFlow recognizes communications as end-to-end flows and performs path control, failure recovery, load balancing, and optimization on a per-flow basis. An OpenFlow switch according to Non Patent Literature 2 has a secure channel for communication with an OpenFlow controller that serves as a control apparatus. In addition, the OpenFlow switch operates according to a flow table suitably added or rewritten by the OpenFlow controller. In a flow table, a set of the following three is defined for each flow: matching rules (Header Fields) against which a packet header is matched; flow statistical information (Counters); and Actions that define processing contents (see FIG. 7).
For example, if the OpenFlow switch receives a packet, the OpenFlow switch searches the flow table for an entry having a matching rule (see Header Fields in FIG. 7) that matches header information of the incoming packet. If the OpenFlow switch finds an entry matching the incoming packet as a result of the search, the OpenFlow switch updates the flow statistical information (Counters) and processes the incoming packet based on a processing content (packet transmission from a specified port, flooding, drop, etc.) written in the Actions field of the entry. If the OpenFlow switch does not find an entry matching the incoming packet as a result of the search, the OpenFlow switch forwards the incoming packet to the OpenFlow controller via the secure channel, to request the OpenFlow controller to determine a packet path based on the source and destination nodes of the incoming packet. After receiving a flow entry realizing the packet path, the OpenFlow switch updates the flow table. In this way, by using an entry stored in the flow table as a processing rule, the OpenFlow switch executes packet forwarding.
Patent Literature 2 discloses a data processing system which transfers broadcast data only to nodes belonging to a certain closed group among the nodes in a single network. Specifically, in the data processing system disclosed in Patent Literature 2, broadcast data outputted from one node is acquired, and a source address is acquired from the acquired broadcast data. Addresses for forwarding the broadcast data only to the nodes other than the node corresponding to the source address, these nodes belonging to the group corresponding to the acquired source address, are acquired from group management information. The group management information defines a correspondence relationship between the group and the address of each node belonging to the group. The destination addresses of the acquired broadcast data are determined as the destination addresses acquired from the group management information and the broadcast data is forwarded to the other nodes via a network.